8,140 research outputs found
Perturbations of Single-field Inflation in Modified Gravity Theory
In this paper, we study the case of single field inflation within the
framework of modified gravity theory where the gravity part has an arbitrary
form . Via a conformal transformation, this case can be transformed into
its Einstein frame where it looks like a two-field inflation model. However,
due to the existence of the isocurvature modes in such a
multi-degree-of-freedom (m.d.o.f.) system, the (curvature) perturbations are
not equivalent in two frames, so in despite of its convenience, it is illegal
to treat the perturbations in its Einstein frame as the "real" ones as we
always do for pure theory or single field with nonminimal coupling. Here
by pulling the results of curvature perturbations back into its original Jordan
frame, we show explicitly the power spectrum and spectral index of the
perturbations in the Jordan frame, as well as how it differs from the Einstein
frame. We also fit our results with the newest Planck data. Since there are
large parameter space in these models, we show that it is easy to fit the data
very well.Comment: 9 pages, 1 figure, substantially improved, matching with the
published versio
Socioeconomic Study on Farmers’ Adoption of Integrated Pest Management (IPM) Strategies in Brassica Vegetable Crops in China
Crop Production/Industries,
Elegant design of carbon nanotube foams with double continuous structure for metamaterials in a broad frequency range
Carbon nanotube (CNT) foams with negative permittivity and permeability are successfully prepared by chemical vapor deposition (CVD) and post-treatment. A double negative metamaterial in the 1-1000 MHz frequency range with double continuous structure results by effectively compounding the CNT foam with a polymer material, i.e. epoxy or nanosilver silicone resin. The negative permeability is specifically attributed to the three-dimensional CNT interactions as clear from the study of the relation of the material microstructure and the macroscopic measurements. Compared to CNT foam/epoxy composites, CNT foam/nanosilver/silicone composites have a lower permeability but a more excellent electrical conductivity or permittivity. It is also shown that the carbon source time during CVD and post-pressurization can be adjusted to allow for both negative permittivity and permeability. This contribution highlights a convenient method to obtain a metamaterial in a much larger frequency range (ca. 1 to 1000 MHz) than the state-of-the-art. It thus supports the expansion of the application range of metamaterials and simplifies their preparation, which is of great significance for the wider use of these materials
Preparation and electrochemical performance of hollow activated carbon fiber self-supported electrode for supercapacitor
Hollow activated carbon fiber (HACF) with high specific surface area and high charge storage capability was prepared by pre-oxidation, carbonization and KOH-activation from polyacrylonitrile (PAN). HACF was used as self-supported working electrode directly without any binder and conductive agent. The effect of the activation time on specific surface area of HACF was studied intensively. The results show that the specific surface area of HACF increased with the increase of activation time from 0.5 h to 1.5 h, and then decreased with further increase of activation time. Highest specific surface area of 1873 m(2)g(-1) and micropore volume of 0.61 cm(3)g(-1) were obtained in HACF activated for 1.5 h. Electrochemical properties of HACF can be improved with increase of activation time, but excessive activation results in the decrease of specific surface area and increase of internal resistance of HACF. The self-supported electrode of HACF possesses a large specific capacitance of 323 F g(-1) at 0.05 A g(-1) and 216 F g(-1) at 1 A g(-1). Therefore, HACF can be a promising self-supported electrode for high performance supercapacitors
The Cost of Obeying the Law?: The Seventh Circuit Rejects the Bona Fide Error Defense from a Debt Collector Who Followed the Then-Binding Law
It is expected that people should follow the law, which includes the statutes themselves and the judicial rulings interpreting those statutes. However, if the binding judicial interpretation changes, should the parties be liable for their behavior following the old binding judicial interpretation of a federal statute at the time when it was still in effect? Or, should there be any defense that would allow the parties to shield themselves from liability for a good-faith reliance on the old binding judicial interpretation
Periodic Radio Variability in NRAO 530: Phase Dispersion Minimization Analysis
In this paper, a periodicity analysis of the radio light curves of the blazar
NRAO 530 at 14.5, 8.0, and 4.8 GHz is presented employing an improved Phase
Dispersion Minimization (PDM) technique. The result, which shows two persistent
periodic components of and years at all three frequencies,
is consistent with the results obtained with the Lomb-Scargle periodogram and
weighted wavelet Z-transform algorithms. The reliability of the derived
periodicities is confirmed by the Monte Carlo numerical simulations which show
a high statistical confidence. (Quasi-)Periodic fluctuations of the radio
luminosity of NRAO 530 might be associated with the oscillations of the
accretion disk triggered by hydrodynamic instabilities of the accreted flow.
\keywords{methods: statistical -- galaxies: active -- galaxies: quasar:
individual: NRAO 530}Comment: 8 pages, 5 figures, accepted by RA
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